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Session 102 - Pulsating Stars.
Display session, Thursday, January 18
North Banquet Hall, Convention Center
By deriving spectroscopic temperatures over pulsational cycles for a set of 11 galactic cepheids and using published photometry, we will complete the calibration of color-temperature relations. These calibrations will be useful in future studies. One key issue is the metallicity sensitivity of the cepheid P-L relation. Baade-Wesselink studies will contribute to these tests, but they require the best color-temperature relations. For example, we (with W. Freedman, B. Madore, and J. Storm) have completed data acquisition for several Galactic, LMC, and SMC cepheids to study this problem, but the temperature scale must be settled first. Further, data acquisition should be completed later this semester for the cepheid V42 in the globular cluster M5, where we have already published Baade-Wesselink analyses for two RR Lyraes. This will help tie those two cepheid and RR Lyrae distances scales together, as will our work in the Clouds. A second goal is that extragalactic cepheids can be subjected to abundance analyses with the new 8m and 10m telescopes, but again, a good set of color-temperature relations will be necessary (at low S/N, we can estimate [m/H] for cepheids throughout the Local Group; at high S/N, we can determine [X/Fe] for selected stars).
